The invention incorporates by reference herein the material of the file identified as xe2x80x9cEF14xe2x80x9d included herewith on one compact disc.
The invention relates to the field of devices for stowing cables. More specifically, to a method for guiding and stowing cable of varying width on a rotating drum.
Levelwinding systems have been used on cable handling systems for many years to smoothly guide cable of uniform width onto storage drums. These systems were mechanical in nature and had to be designed for a cable of a particular width. In general a mechanical system would have a sprocket gear mounted on one side of the drum that transferred the rotations of the drum via a chain drive to the levelwind. The rotations were transferred to the levelwind diamond screw that moved a shuttle back and forth across the face of the drum. The cable would pass through rollers on the shuttle and be guided onto the drum. The levelwind speed was set by the gear ratio of the chain drive as well as the pitch of the diamond screw and could not be dynamically changed. In a mechanical levelwind if the width of the cable changed, the system would have to have some mechanical redesign to the gears or diamond screw to accommodate the new width of the cable by speeding up or slowing down the levelwind shuttle. With a cable that has a varying width the drum was usually segmented and the levelwind system required interaction with the operator. The shuttle levelwinds back-and-forth on the first segment of the drum. When the wider width cable needs to be wrapped, the operator would manually transition the shuttle to the next segment of the drum.
Cables that are designed to tow devices, such as a sonar array, through the water are generally faired. Fairing on the cable reduces drag and strumming of the cable as it is towed through the water. Strumming can damage or break the cable and damage or negatively interfere with the device that is being towed. There are two types of fairing used in marine cables, soft fairing and hard fairing. A cable that has soft fairings, such as plastic ribbon or fiber xe2x80x9chairyxe2x80x9d fairing, can cause unpredictable gapping during wrapping due to bunching up of the fairing in a random fashion.
Cable that has hard fairing is traditionally wrapped on a segmented, grooved drum to prevent slipping or leaning of the hard fairing. When hard-faired cable is wrapped on top of a previous layer of cable or on a smooth drum surface, slipping or leaning of the fairing produces random gaps in the wrap. For this reason hard-faired cable is not traditionally wrapped over bare or soft-faired cable. In either case a mechanical levelwinding system has no way of compensating for these conditions.
Thus, in accordance with this inventive concept, a need has been recognized in the state of the art for a system to guide a cable onto a rotating drum to prevent the cable from bunching unevenly on the drum or gapping and to accommodate cable of varying width.
An object of the invention is to provide a system to guide a cable onto a rotating drum to prevent the cable from bunching unevenly on the drum or gapping between adjacent wraps.
Another object of the invention is to provide a system to accommodate cable of any width on a rotating drum.
Another object of the invention is to provide a system to accommodate a cable of varying width such as a marine cable that is faired on a rotating drum.
Another object is to provide a system to accommodate changes in the geometry of the system""s cable by functionally altering the operation of a levelwind mechanism via a simple programmed change instead of a costly mechanical redesign.
Another object is to provide a system to utilize active feedback to maintain a shuttle in its optimal position for a smooth wrap of cable on a rotating drum.
Another object is to provide a feedback system to detect and give alerts of a potentially dangerous condition to operators if a cable being wrapped develops gaps or bunches.
Another object is to provide a system having significant weight and size reductions over contemporary mechanical designs.
Another object is to provide a system eliminating the need for a heavy, expensive grooved drum by allowing hard-faired cable to be wrapped on top of bare or soft-faired cable.
Another object is to provide a programmable stepper motor to guide a cable of varying width on and off a rotating storage drum in smooth and orderly fashion to maximize the storage capacity of the drum.
Another object is to provide a levelwind system utilizing feedback sensors to monitor the position of incoming cable.
Another object is to provide a levelwind system making correction movements of a levelwind shuttle when an incoming cable assumes a different geometry.
Another object is to provide a system using a relatively small and inexpensive stepper motor, instead of hazardously exposed chain and gear drives that should be covered to protect the operators from injury, to reduce size, weight, and cost as compared to conventional mechanical systems.
Another object is to provide a system having a conventional computer providing visual graphical interfaces for the operator to provide real-time indications of the cable wrapping process.
Another object is to provide a system to using cost effective, proven off-the-shelf consumer technology that can be purchased from numerous vendors.
These and other objects of the invention will become more readily apparent from the ensuing specification when taken in conjunction with the appended claims.
Accordingly, the present invention is an apparatus and method to wind cable on a drum. A rotary encoder provides signals representative of rotation of the drum and a platform adjacent to the drum has a shuttle receiving the cable and can be bidirectionally moved to wrap the cable on the drum. A limit switch at each end of the platform provides a limit signal when contacted by the shuttle. An outboard sensor assembly on the shuttle extends outboard to receive an outboard extending portion of the cable and has an outboard angular sensor providing signals representative of its angular extension. An inboard sensor assembly on the shuttle extends inboard to receive an inboard extending portion of the cable and has an inboard angular sensor providing signals representative of its angular extension. A computer responsive to the outboard and inboard sensor signals generates error position feedback signals and is connected to a stepper motor coupled to the shuttle to bidirectionally displace the shuttle and the cable in response to the rotation signals, limit signals, outboard angular signals and inboard angular signals to smoothly wind the cable that may be of varying width.